Vehicle occupant sensing system having guiding ribs

ABSTRACT

A vehicle occupant sensing system for detecting a condition of a vehicle seat assembly. The vehicle occupant sensing system includes a base, an upper slide member supported for movement toward and away from the base, and at least one guiding rib. The guiding rib extends from one of the upper slide member and the base toward the other of the upper slide member and the base so as to guide movement of the upper slide member toward and away from the base. The vehicle occupant sensing system may be employed in a vehicle seat assembly to detect a condition of the vehicle seat.

CROSS REFERENCE TO RELATED APPLICATION

The following is a continuation-in-part of U.S. Ser. No. 10/974,101, filed Oct. 27, 2004, and entitled “Vehicle Occupant Sensing System Having a Contamination Barrier Member.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, generally, to a vehicle occupant sensing system, and more particularly, to a vehicle occupant sensing system having guiding ribs.

2. Description of the Related Art

Automotive vehicles employ seating systems that accommodate the passengers of the vehicle. The seating systems include restraint systems that are calculated to restrain and protect the occupants in the event of a collision. The primary restraint system commonly employed in most vehicles today is the seatbelt. Seatbelts usually include a lap belt and a shoulder belt that extends diagonally across the occupant's torso from one end of the lap belt to a mounting structure located proximate to the occupant's opposite shoulder.

In addition, automotive vehicles may include supplemental restraint systems. The most common supplemental restraint system employed in automotive vehicles today is the inflatable airbag. In the event of a collision, the airbags are deployed as an additional means of restraining and protecting the occupants of the vehicle. Originally, the supplemental inflatable restraints (airbags) were deployed in the event of a collision whether or not any given seat was occupied. These supplemental inflatable restraints and their associated deployment systems are expensive and over time this deployment strategy was deemed not to be cost effective. Thus, there became a recognized need in the art for a means to selectively control the deployment of the airbags such that deployment occurs only when the seat is occupied.

Partially in response to this need, vehicle safety systems have been proposed that include vehicle occupant sensing systems capable of detecting whether or not a given seat is occupied. The systems act as a switch in controlling the deployment of a corresponding air bag. If the occupant sensing device detects that a seat is unoccupied during a collision, it can prevent the corresponding air bag from deploying, thereby saving the vehicle owner the unnecessary cost of replacing the expended air bag.

Furthermore, many airbag deployment forces and speeds have generally been optimized to restrain one hundred eighty pound males because the one hundred eighty pound male represents the mean average for all types of vehicle occupants. However, the airbag deployment force and speed required to restrain a one hundred eighty pound male exceeds that which are required to restrain smaller occupants, such as some females and small children. Thus, there became a recognized need in the art for occupant sensing systems that could be used to selectively control the deployment of the airbags when a person below a predetermined weight occupies the seat.

Accordingly, other vehicle safety systems have been proposed that are capable of detecting the weight of an occupant. In one such inflatable restraint system, if the occupant's weight falls below a predetermined level, then the system can suppress the inflation of the air bag or will prevent the air bag from deploying at all. This reduces the risk of injury that the inflating air bag could otherwise cause to the smaller-sized occupant.

Also, many airbag deployment forces and speeds have generally been optimized to restrain a person sitting generally upright toward the back of the seat. However, the airbag deployment force and speed may inappropriately restrain a person sitting otherwise. Thus, there became a recognized need in the art for a way to selectively control the deployment of an airbag depending on the occupant's sitting position.

Partially in response to this need, other vehicle safety systems have been proposed that are capable of detecting the position of an occupant within a seat. For example, if the system detects that the occupant is positioned toward the front of the seat, the system will suppress the inflation of the air bag or will prevent the air bag from deploying at all. This reduces the risk of injury that the inflating air bag could otherwise cause to the occupant. It can be appreciated that these occupant sensing systems provide valuable data, allowing the vehicle safety systems to function more effectively to reduce injuries to vehicle occupants.

One necessary component of each of the known systems discussed above includes some means for sensing the presence of the vehicle occupant in the seat. One such means may include a sensor device supported within the lower seat cushion of the vehicle seat. For example, published U.S. patent application having U.S. Ser. No. 10/249,527 and Publication No. US2003/0196495 A1 filed in the name of Saunders et al. discloses a method and apparatus for sensing seat occupancy including a sensor/emitter pair that is supported within a preassembled one-piece cylinder-shaped housing. The housing is adapted to be mounted within the seat cushion in a hole extending from the B-surface toward the A-surface of the seat cushion. The sensor/emitter pair supported in the housing includes an emitter and a sensor spaced below the emitter. The cylindrical housing is formed of a compressible, rubber-like material that is responsive to loads placed on the upper surface of the seat cushion. The housing compresses in response to a load on the seat cushion. The load is detected through movement of the emitter toward the sensor as the housing is compressed. The housing is sufficiently resilient to restore the emitter to full height when no load is applied to the upper surface of the seat cushion. The Saunders et al. system also includes a processor for receiving the sensor signals and interpreting the signals to produce an output to indicate the presence of an occupant in the seat.

While the Saunders et al. occupant seat sensing system may sense the presence of a vehicle seat occupant, it suffers from certain disadvantages. For example, the housing may flex in an undesired manner in response to loading of the seat cushion thereby moving the emitter in an undesired direction relative to the sensor. As such, occupant detection can be inaccurate. Flexure of the housing may also causing excess signal noise to be generated within the system.

Therefore, there is an ongoing need in the art for a vehicle occupant sensing system that can detect vehicle occupants more accurately. There is also an ongoing need in the art for a vehicle occupant sensing system that creates less signal noise during occupant detection.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages in the related art in a vehicle occupant sensing system for detecting a condition of a vehicle seat assembly. The vehicle occupant sensing system includes a base, an upper slide member supported for movement toward and away from the base, and at least one guiding rib. The guiding rib extends from one of the upper slide member and the base toward the other of the upper slide member and the base so as to guide movement of the upper slide member toward and away from the base. The vehicle occupant sensing system may be employed in a vehicle seat assembly to detect a condition of the vehicle seat.

The guiding ribs guide the movement of the upper slide member toward and away from the base by limiting tilt of the upper slide member as it moves. The guiding ribs also reduce friction as the upper slide member moves, thereby improving the response of the upper slide member and reducing signal noise in the vehicle occupant sensing system during loading of the vehicle seat assembly.

Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a vehicle seat assembly incorporating a vehicle occupant sensing system having contamination barrier members that act to reduce contamination of the vehicle occupant sensing system;

FIG. 2 is an exploded view of one embodiment of a sensor assembly suitable for use in the vehicle occupant sensing system illustrated in FIG. 1;

FIG. 3 is a cross-sectional side view of the sensor assembly of FIG. 2 shown in a compressed state;

FIG. 4 is a cross-sectional side view of the sensor assembly of FIG. 2 shown in an uncompressed state;

FIG. 5 is an exploded top view of another embodiment of a vehicle occupant sensing system having contamination barrier members;

FIG. 6 is an exploded bottom view of the vehicle occupant sensing system of FIG. 5;

FIG. 7 is a cross-sectional side view of the sensor assembly of FIG. 5;

FIG. 8 is a cross-sectional side view of the sensor assembly of FIG. 7 taken along the line 8-8; and

FIG. 9 is a cross-sectional top view of the sensor assembly of FIG. 7 taken along the line 9-9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, where like numerals are used to designate like structure throughout the figures, an exploded view of one embodiment of the vehicle seat assembly of the present invention is generally indicated at 10 in FIG. 1. The vehicle seat assembly 10 includes a seat back, generally indicated at 12, and a lower seat assembly, generally indicated at 14. The lower seat assembly 14 has a seat cushion 16 with an upper surface 18 and a lower surface 20 that is spaced from the upper surface 18. The upper surface 18 of the seat cushion 16 may be referred to as the “A-surface” and the lower surface 20 may be referred to as the “B-surface.” The seat cushion 16 also defines an inboard side 22 and an outboard side 24. When an occupant (not shown) is supported on the lower seat assembly 14, the weight of the occupant will apply an axial load directed generally through the upper surface 18 of the seat cushion 16 toward the lower surface 20. Although the weight of the occupant will induce an axial as well as shear forces in the seat cushion 16, those having ordinary skill in the art will recognize that the primary load path of the occupant's weight will be substantially vertical from the upper surface 18 toward the lower surface 20, through the seat cushion 16.

The lower seat assembly 14 also includes a seat pan, generally indicated at 26. The seat pan 26 is generally disposed beneath the lower surface 18 so as to support the seat largely unaffected by shear forces in the seat cushion 16. Furthermore, the ribs 80 reduce surface area contact between the upper slide member 46 and the inner surface 72 of the base 44. In turn, the ribs 80 reduce friction between the upper slide member 46 and the base 44 as the upper slide member 46 moves. The ribs 80 and the inner surface 72 can also be polished in order to further reduce friction.

In the embodiment shown, the ribs 80 include lower ends 84 extending away from the lower edge of the support wall 78. The platform 60 includes openings 86 positioned below the lower ends 84 formed on each rib 80. The tray 30 also includes pockets 88 positioned below the lower ends 84 and the openings 86. Preferably, the lower ends 84, the openings 86, and the pockets 88 are aligned such that the lower ends 84 move through the openings 86 and into the pockets 88. Advantageously, these features allow the upper slide member 46 to move farther toward the base 44, such that the sensor assembly 42 is less likely to detrimentally affect the comfort of the vehicle seat assembly 10.

The upper slide member 46 also includes at least one, and preferably, a plurality of lower flange members 82. The lower flange members 82 are each triangular shaped, extend from a lower edge of the support wall 78, and face outwardly therefrom. The lower flange members 82 are spaced according to that of the upper flange members 74 of the base 44. To attach the upper slide member 46 to the base 44, the upper slide member 46 is moved axially toward the base 44 until the lower flange members 82 contact the upper flange members 74. Further movement of the upper slide member 46 bends the lower flange members 82 inward, and still further movement allows the lower flange members 82 to bend back underneath the upper flange members 74. Once attached, movement of the upper slide member 46 away from the base 44 eventually causes the lower flange members 82 to contact the upper flange members 74. Thus, the lower flange members 82 and the upper flange members 74 cooperate to define the limit of sliding movement of the upper slide member 46 away from the base 44.

On the other hand, the platform 60 of the base 44 and the lower edge of the support wall 78 of the upper slide member 46 cooperate to define the limit of sliding movement of the upper slide member 46 toward the base 44. More specifically, as the upper slide member 46 moves toward the base 44, the lower edge of the support wall 78 contacts the platform 60 of the base 44, thereby limiting further movement. The lower ends 84 of the ribs 80 and the tray 20 can cooperate to define the limit of movement of the upper slide member 46 toward the base 44 in addition to or as an alternative to the support wall 78 and platform 60.

Furthermore, the upper slide member 46 includes a retainer 90. The retainer 90 is cup-shaped and extends in the general direction of the base 50 from the center of the upper disc portion 76 of the upper slide member 46. The emitter 50 is disposed within the retainer 90, and the bottom and sides of the emitter 50 are supported therein. As shown in FIGS. 3 and 4, the retainer 90 includes slots 92 extending across the bottom surface of the emitter 50, thereby partially exposing the bottom surface of the emitter 50.

In the embodiment shown, the upper slide member 46 also includes an interference member 94. The interference member 94 can be built according to applicant's co-pending application, U.S. Ser. No. 10/899,192, entitled “Vehicle Occupant Sensing System Having an Upper Slide Member with an Emitter Interference Member” and filed Jul. 26, 2004. In the embodiment shown, the interference member 94 is generally flat and is hingeably attached at one end to the upper disc portion 76 of the upper slide member 46. The interference member 94 includes a plurality of clips 96, and the upper disc portion 76 includes a corresponding plurality of apertures 98. The interference member also includes an opening 100 with an interference arm 102 that extends from the periphery of the opening 100 into the opening 100. As such, when the emitter 50 is positioned within the retainer 90, the interference member 94 can be pivoted over the retainer 90, and the clips 96 can be attached within the apertures 98 to the upper slide member 46. With the interference member 94 in this position, the interference arm 102 preferably contacts and biases the emitter 50 into the retainer 90. Thus, the interference member 94 mounts the emitter 50 to the upper slide member 46 in a more robust manner.

As stated above, the sensor assembly 42 includes a biasing member 48. The biasing member 48 is a coiled spring in the embodiment shown. As best seen in FIGS. 3 and 4, one end of the biasing member 48 is supported by a mounting surface 104 the platform 60 of the base 44. The platform 60 includes ridge 106 extending upward from and centered about the mounting surface 104 to thereby keep the biasing member 48 centered atop the mounting surface 104. The opposite end of the biasing member 48 is disposed about the retainer 90 and contacts the bottom surface of the upper disc portion 76 of the upper slide member 46 such that the biasing member 48 biases the upper slide member 46 away from the base 44. Preferably, the biasing member 48 causes the lower flange members 82 of the upper slide member 46 to contact the upper flange members 74 of the base 44 when the seat cushion is unoccupied.

The platform 60 of the base 44 also includes an opening 107 positioned at the center of the base 44. The opening 107 provides clearance for the sensor 52. Preferably, the sensor 52 is aligned with the emitter 50 as the upper slide member 46 moves toward and away from the base 44 for accurate detection of the distance between the emitter 50 and sensor 52.

Thus, the base 44 and the upper slide member 46 cooperate to define an interior cavity 108 of the sensor assembly 42. The sensor 52 and the biasing member 48 are disposed within the interior cavity 108. Contamination of the interior cavity 108 may cause the sensor 52 and/or biasing member 48 to malfunction. For example, dust particles and/or foam particles from the seat cushion 16 could enter the interior cavity 108 and inhibit the upper slide member 46 from moving in its preferred manner. Likewise, rainwater or other liquids could enter the interior cavity 108 and cause the sensor 52 to malfunction. Thus, the vehicle occupant sensing system 28 of the present invention includes the contamination barrier member 54 to at least partially encapsulate the upper slide member 46 and base 44 so as to decrease contamination of the interior cavity 108 of the sensor assembly 42.

In the embodiment shown, the barrier member 54 is a single, unitary member that includes a flat, upper platform 110 and a wall 112. The wall 112 is contoured to accommodate the shape of the sensor assembly 42. To this end, in the embodiment shown, the wall 112 initially extends downward from the periphery of the upper platform 110, then bends upward 180° at a first bend 114, and then bends downward 180° at a second bend 116. The barrier member 54 also includes a lower flange 118, which is integrally attached to the lower terminal end of the wall 112 and extends outwardly therefrom in a horizontal direction as best seen in FIG. 2. The lower flange 118 includes a plurality of recesses 119 located to provide clearance for the retaining ridges 64 of the base 44 when the barrier member 54 is attached to the base 44. The barrier member 54 defines an opening 120 on its lower end, and the upper slide member 46 and the base 44 pass through the opening 120 when attaching the barrier member 54.

The barrier member 54 also includes at least one retaining rail, generally indicated at 122, for operatively attaching the barrier member 54 to the base 44. In the embodiment shown, there are a plurality of first retaining rails 124, and a plurality of second retaining rails 126. The first retaining rails 124 are generally straight and extend downward from the lower flange 118 of the barrier member 54. The first retaining rails 124 are spaced opposite each other on the barrier member 54. The base 44 also includes at least one slot 128 of a shape and location corresponding to that of the first retaining rails 124. In the embodiment shown, there are slots 128 adjacent each retaining ridge 64 of the base 44. Each slot 128 is generally straight and extends through the retainer 58 of the base 44. As best shown in FIG. 4, the first retaining rails 124 of the barrier member 54 are retained within the corresponding slots 128 of the base 44 to operatively attach the barrier member 54 to the base 44. Each of the first retaining rails 124 also includes a bulbous head 130 to attach the barrier member 54 to the base 44 in a more robust manner.

The second retaining rails 126 are generally straight and extend downward from the lower flange 118 of the barrier member 54. The second retaining rails 126 each include a head 132, at which the rail 126 turns inward toward the center of the barrier member 54. The second retaining rails 126 are spaced opposite each other on the barrier member 54 and are located 90° away from the first retaining rails 124. The base 44 also includes recesses 134 on the periphery of the retainer 58 in locations corresponding to that of the second retaining rails 126. As best shown in FIG. 3, the second retaining rails 126 extend through the recesses 134, and the heads 132 are operatively attached to the bottom side 61 of the base 44. The tray 30 includes pockets 88 into which the second retaining rails 126 extend to allow the heads 132 to attach to the bottom side 61 of the base 44. In the preferred embodiment, the pockets 88 are sufficiently shallow such that the upper surface 32 of the tray 30 forces the second retaining rails 126 into the bottom side 61 of the base 44 for improved retention of the barrier member 54 to the base 44.

Furthermore, the upper surface 32 of the tray 30 includes at least one, and preferably, a plurality of posts 136. The posts 136 extend upwardly from the upper surface 32 of the tray 30 and are spaced opposite each other about the sensor assembly 42. The posts 136 are positioned and sized such that the posts 136 force the second retaining rails 126 of the barrier member 54 against the periphery of the retainer 58 of the base 44 as best shown in FIG. 3. Thus, the posts 136 further improve retention of the barrier member 54 to the base 44.

In the embodiment shown, the barrier member 54 and the upper surface 32 of the tray 30 cooperate to substantially encapsulate the upper slide member 46 and the base 44. Those of ordinary skill in the art, however, will recognize that the barrier member 54 could be configured to solely encapsulate the upper slide member 46 and the base 44 without departing from the scope of the invention.

The barrier member 54 is preferably made of a resiliently flexible material, such as rubber. As such, the barrier member 54 can flex and allow the upper slide member 46 to move relative to the base 44. The barrier member 54 inhibits contaminants, such as foam particles, rainwater, or other foreign substances, from contacting and detrimentally affecting the operation of the sensor assembly 42 and sensor 52. As such, the barrier members 54 extend the operating life of the vehicle occupant sensing system 28.

Referring now to FIGS. 5 through 8, a second embodiment of the vehicle occupant sensing system is generally indicated at 228 where like numerals increased by 200 are used to designate like structure with respect to the embodiment illustrated in FIGS. 2 through 4. The vehicle occupant sensing system 228 can be employed in the vehicle seat assembly 10 of FIG. 1.

The vehicle occupant sensing system 228 includes a circuit carrier tray 230 and a circuit carrier 234 that is similar to the embodiment shown in FIGS. 2 through 4 except as noted below. The vehicle occupant sensing system 228 also includes at least one, and preferably, a plurality of sensor assemblies, generally indicated at 242. Those having ordinary skill in the art will appreciate that although FIG. 5 shows only one sensor assembly 242, the vehicle occupant sensing system 228 of the present invention could employ any number of sensor assemblies 242, including an array of sensor assemblies 242 like that shown in FIG. 1.

The sensor assemblies 242 include a base, generally indicated at 244, and an upper slide member, generally indicated at 246. The upper slide member 246 is supported for movement toward and away from the base 244 as will be discussed in greater detail below. The sensor assembly 242 also includes a biasing member 248 that biases the upper slide member 246 away from the base 244. The vehicle occupant sensing system 228 also includes at least one, and preferably, a plurality of sensors 252. The sensors 252 are operatively attached to the circuit carrier 234 and are similar to the sensors 52 discussed above in relation to FIGS. 2 through 4. Furthermore, the vehicle occupant sensing system 228 includes at least one, and preferably, a plurality of emitters 250 similar to the emitters 50 discussed above in relation to FIGS. 2 through 4. Each sensor assembly 242 includes an associated emitter 250 and sensor 252 as shown in FIG. 5.

The vehicle occupant sensing system 228 of the present invention further includes at least one guiding rib 280 extending from at least one of the upper slide member 246 and the base 244 toward the other of the upper slide member 246 and the base 244 (FIGS. 6, 7 and 9). The guiding ribs 280 guide movement of the upper slide member 246 toward and away from the base 244 as will be discussed in greater detail below.

Specific features of the sensor assembly 242 and vehicle occupant sensing system 228 shown in FIGS. 5-8 will now be discussed. As shown, the base 244 generally includes a base guide 256 and a retainer 258. The retainer 258 is flat and is positioned atop the circuit carrier 234. The base guide 256 is generally tubular and is attached at one terminal end to the retainer 258, extending axially therefrom toward the seat cushion 16. The base 244 also includes an interior ridge 260 as shown in FIGS. 7 and 8. The interior ridge 260 is also tubular, is attached at one terminal end to the retainer 258, and extends axially from the retainer 258 toward the seat cushion 16. In the embodiment shown, the interior ridge 260 is disposed within the base guide 256 and is axially centered therein.

The retainer 258 includes a plurality of retaining ridges 264. The ridges 264 curve inward from the outer periphery of the retainer 258 and extend away from a topside 262 of the retainer 258 toward the seat cushion 16. In the embodiment shown, the ridges 264 are disposed on opposite sides of the retainer 258. The tray 230 includes a plurality of clips 266 for mounting the base 244 to the tray 230. The clips 266 each extend from the upper surface 232 of the tray 230, through apertures 270 in the circuit carrier 234, and toward the base 244 (FIG. 5). The clips 266 each include an enlarged head 268. To mount the base 244 to the tray 230, the base 244 is positioned between the heads 268 and moved axially toward the upper surface 232 of the tray 230. As the heads 268 contact the retaining ridges 264, the clips 266 bend outwardly. When the retaining ridges 264 move past the heads 268, the clips 266 resiliently bend back toward the retaining ridges 264 and the heads 268 move over the retaining ridges 264, thereby mounting the base 244 to the tray 230.

The base guide 256 has an inner surface 272 as shown in FIGS. 5, 7, and 8. The base guide 256 includes at least one, and preferably, a plurality of upper flange members 274. The flange members 274 are each triangular shaped, are disposed at ninety degrees (90°) away from each other on a rim 275 of the base guide 256, and face inwardly from the inner surface 272 toward the axis A. The inner surface 272 of the base guide 256 is used to guide movement of the upper slide member 246, and the upper flange members 274 are used to limit movement of the upper slide member 246 as will be discussed in greater detail below.

As shown in FIGS. 6-8, the upper slide member 246 includes an upper disc portion 276 and a support wall 278. The upper disc portion 276 is generally flat and is preferably disposed parallel to the retainer 258 of the base 244. The support wall 278 is generally rectangular and tubular and extends axially from the upper disc portion 276 toward the base 244. The support wall 278 is sized according to the inner surface 272 of the base guide 256 such that the support wall 278 can be moveably disposed within the base guide 256.

The upper slide member 246 also includes at least one, and preferably, a plurality of lower flange members 282 (FIGS. 6 and 8). The lower flange members 282 are each triangular shaped and extend from a lower edge of the support wall 278 away from the axis A. The lower flange members 282 are disposed on the upper slide member 246 according to that of the upper flange members 274 of the base 244.

To attach the upper slide member 246 to the base 244, the upper slide member 246 is moved axially toward the base 244 until the lower flange members 282 contact the upper flange members 274. Further movement of the upper slide member 246 moves the lower flange members 282 toward the axis A, and once the lower flange members 282 move past the upper flange members 274, the lower flange member 282 resiliently move underneath the upper flange members 274. Once attached, the biasing member 248 biases the upper slide member 246 away from the base 244 into a fully extended position (FIGS. 7 and 8) in which the lower flange members 282 contact the upper flange members 274. The upper slide member 246 can also be moved against the biasing force of the biasing member 248 toward the base 244 such that the support wall 278 of the upper slide member 246 moves axially within the interior of the base 244.

The sensor assembly 242 also includes a plurality of U-shaped channels 257 (FIG. 5) that extend away from the interior of the base guide 256 and a plurality of stiffening ribs 263 that extend axially from the base guide 256 away from the axis A. In the embodiment shown, the channels 257 are disposed on opposite sides of the base guide 256, the stiffening ribs 263 are also disposed on opposite sides of the base guide 256, and the channels 257 are disposed ninety degrees (90°) away from the stiffening ribs 263.

The upper slide member 246 also includes at least one, and preferably, a plurality of alignment ribs 281 (FIG. 6). The alignment ribs 281 are attached to the support wall 278 and extend away from the axis A. Preferably, the number, size, and location of the alignment ribs 281 correspond to that of the channels 257 of the base 244. When the upper slide member 246 is attached to the base 244, the alignment ribs 281 are disposed within the channels 257 and move axially therein when the upper slide member 246 moves. However, the alignment ribs 281 and channels 257 abut if the upper slide member 246 rotates about the axis A. Because rotation of the upper slide member 246 is substantially inhibited, the orientation of the emitter 250 remains more consistent in relation to the sensor 252 such that the vehicle occupant sensing system 228 provides more accurate detection of the condition of the vehicle seat assembly 10.

Furthermore, the upper slide member 246 includes a retainer 290. The retainer 290 is cup-shaped and extends axially toward the base 250 from the center of the upper disc portion 276 of the upper slide member 246. The emitter 250 is disposed within the retainer 290, and the bottom and sides of the emitter 250 are supported therein. As shown in FIG. 6, the retainer 290 includes apertures 292 that partially expose the bottom surface of the emitter 250. In the embodiment shown, the upper slide member 246 also includes at least one interference member 294 (FIGS. 5 and 7). The interference member 294 can be built according to applicant's co-pending application, U.S. Ser. No. 10/899,192, entitled “Vehicle Occupant Sensing System Having an Upper Slide Member with an Emitter Interference Member” and filed Jul. 26, 2004. In the embodiment shown, the interference members 294 each include a side portion 295 that is hingeably and resiliently attached to the retainer 290, and each side portion 295 includes a corresponding head 297 that extends radially from the respective side portion 295 toward the axis A. The heads 297 extend over the top of the emitter 250 to hold the emitter 250 within the retainer 290. The side portions 295 move radially away from the axis A in order to move the emitter 250 respectively out of and into the retainer 290. Thus, the interference member 294 mounts the emitter 250 to the upper slide member 246 in a more robust manner.

The retainer 258 of the base 244 also includes an opening 307 positioned at the center of the base 244 (FIGS. 6 and 8). The opening 307 is preferably disposed over the sensor 252 such that the sensor 252 can detect the distance to the emitter 250. The opening 307 also provides clearance for the retainer 290 as the upper slide member 246 moves toward the base 244.

The upper slide member 246 also includes at least one contamination barrier member 254 (FIGS. 6-8). The contamination barrier members 254 can be built according to applicant's co-pending application entitled “Vehicle Occupant Sensing System Having a Contamination Barrier Member,” Ser. No. ______, and filed ______, which is hereby incorporated in its entirety by reference. In the embodiment shown, the contamination barrier member 254 includes a ring 340 and a skirt 342. The ring 340 is attached to the upper slide member 246 and is concentric with the upper disc portion 276. Preferably, the ring 340 substantially extends over the subject area 309 to block contaminants from entering the interior cavity 308 of the sensor assembly 242. The skirt 342 generally extends from the outer periphery of the ring 340 toward the base 244 and substantially over the support wall 278 to further block contaminants from entering the interior cavity 308 of the sensor assembly 242. Preferably, the skirt 342 extends far enough toward the base 244 in order to at least partially surround and enclose the rim 275 of the base 244 when the upper slide member 246 is in its fully extended position away from the base 244. As such, the contamination barrier member 254 shields the sensor assembly 242 from contaminants when the upper slide member 246 is in its fully extended position. When the upper slide member 246 moves toward the base 244, the contamination barrier member 254 continues to shield the sensor assembly 242. Specifically, the skirt 342 and the support wall 278 of the upper slide member 246 are disposed in spaced relationship as shown in FIGS. 7 and 8 to define a cavity 344. The base guide 256 is adapted to be disposed within the cavity 344 when the upper slide member 246 moves toward the base 244. The ring 340 moves closer to the subject area 309, and the skirt 342 moves over the base guide 256 for added protection from contaminants. In the preferred embodiment, the skirt 342 is integrally attached to the ring 340, and the ring 340 is integrally attached to the upper slide member 246.

As noted above, the sensor assembly 242 includes a biasing member 248. The biasing member 248 is a coiled spring in the embodiment shown. As best shown in FIGS. 7 and 8, one end of the biasing member 248 is supported on the retainer 258 and within the interior ridge 260 of the base 244. The opposite end of the biasing member 248 is disposed about the retainer 290 such that the biasing member 248 biases the upper slide member 246 away from the base 244. Preferably, the biasing member 248 causes the lower flange members 282 of the upper slide member 246 to contact the upper flange members 274 of the base 244 when the seat cushion is unoccupied. Furthermore, in the embodiment shown, the upper slide member 246 includes at least one, and preferably, a plurality of retention members 299 (FIGS. 6 and 8). The retention members 299 can be built according to applicant's co-pending application Ser. No. ______, entitled “Vehicle Occupant Sensing System Having a Retention Member for a Biasing Member,” and filed ______, which is hereby incorporated in its entirety by reference. In the embodiment shown, there is a plurality of triangular-shaped retention members 299 extending radially on the underside of the upper disc portion 276 and away from the retainer 290. The retention members 299 are evenly spaced about the retainer 290. As shown in FIG. 8, the biasing member 248 is mounted to the upper slide member 246 by positioning the retention members 299 within the biasing member 248. The retention members 299 are held relative to the biasing member 248 by friction. By reducing surface area contact between the upper slide member 246 and the biasing member 248, the retention members 299 reduce friction as the upper slide member 246 moves toward the base 244, thereby reducing signal noise of the sensor 252.

The sensor 252 is operable to detect the relative distance to the emitter 250 similar to the embodiment described above in relation to FIGS. 2-4. Because the emitter 250 is mounted to the upper slide member 246, the sensor 252 is operable to detect movement of the upper slide member 246 toward and away from the base 244. Thus, when the seat cushion 16 is occupied, the upper slide members 246 of each sensor assembly 242 slide accordingly toward the respective bases 244, and the sensors 252 detect the change in distance to the respective emitters 250. The sensors 252 transmit correlative signals to the controller 38, and the controller 38 sends output to the restraint system 40 based on those signals. It should be appreciated that when the seat cushion 16 is unoccupied, the sensors 252 can also detect the relative distance to the respective emitters 250 to detect that the seat assembly 10 is unoccupied as well. Therefore, operation of the restraint system 40 can depend on the condition of the seat assembly 10. For instance, assuming the restraint system 40 is an airbag system and that the vehicle occupant sensing system 228 detects that the seat assembly 10 is unoccupied, the restraint system 40 can disengage and prevent the airbag from deploying. Likewise, if the vehicle occupant sensing system 228 detects that the occupant weighs a certain amount and/or that the occupant is sitting in a certain position, the airbag can be inflated in a manner that safely restrains such an occupant.

As noted above and as shown in FIGS. 6, 7 and 9, the vehicle occupant sensing system 228 includes at least one, and preferably, a plurality of guiding ribs 280. In the embodiment shown, the guiding ribs 280 are axially straight with rounded outer edges 283. The guiding ribs 280 are mounted to the upper slide member 246 and extend toward the base 244. Those having ordinary skill in the art, however, will appreciate that the guiding ribs 280 could be mounted to the base 244 and extend toward the upper slide member 246 as an alternative to or in addition to the guiding ribs 280 shown.

The guiding ribs 280 are spaced apart from each other about the support wall 278 of the upper slide member 246. For instance, in the embodiment shown, there are a plurality of guiding ribs 280 disposed adjacent the corners of the support wall 278 of the upper slide member 246. The guiding ribs 280 are integrally attached to the upper slide member 246 in one embodiment such that the upper slide member 246 and guiding ribs 280 can be more easily made, such as via a molding process of any type commonly known in the art.

In the preferred embodiment, the guiding ribs 280 extend far enough toward the base 244 to slidably contact the inner surface 272 of the base guide 256 (FIGS. 7 and 9). As such, the guiding ribs 280 reduce tilting of the upper slide member 246 relative to the axis, A, and maintains movement of the upper slide member 246 substantially along the axis A. Also, the guiding ribs 280 reduce surface area contact (and thus friction) between the upper slide member 246 and the base 244 to thereby reduce signal noise generated in the vehicle occupant sensing system 228 and improve response of the vehicle occupant sensing system 228 to loading of the vehicle seat assembly 10. The guiding ribs 280 and/or the inner surface 272 of the base guide 256 are preferably polished to further reduce friction for improved response.

In the embodiment shown, the guiding ribs 280 include lower ends 284 (FIGS. 6 and 7) with an axial length, L, that is longer than the axial length, L′, of the support wall 278 of the upper slide member 246. The retainer 258 of the base 244 includes at least one, and preferably, a plurality of first openings 286 (FIGS. 6-8). The circuit carrier 234 also includes at least one, and preferably, a plurality of second openings 287 (FIGS. 5, 7, and 8), and the tray 230 includes at least one, and preferably, a plurality of pockets 288. In the preferred embodiment, the number and size of the first openings 286, second openings 287, and pockets 288 correspond with that of the lower ends 284 of the guiding ribs 280. Also, the first openings 286, second openings, and pockets 288 are axially aligned with the lower ends 284 such that the lower ends 284 of the guiding ribs 280 can enter the first and second openings 286, 287 and extend into the pockets 288 when the upper slide member 246 moves toward the base 244. As such, the upper slide member 246 can move an increased distance toward the base 244 such that the sensor assembly 242 is less likely to detrimentally affect the comfort of the vehicle seat assembly 10.

In summary, the guiding ribs 280 guide the movement of the upper slide member 246 toward and away from the base 244 by limiting tilt of the upper slide member 246 relative to the axis, A, of the sensor assembly 242. The guiding ribs 280 also reduce friction as the upper slide member 246 moves, thereby improving response of the upper slide member 246 and reducing signal noise in the vehicle occupant sensing system 228 during loading of the vehicle seat assembly 10.

The present invention has been described in an illustrative manner. It is to be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described. 

1. A vehicle occupant sensing system for detecting a condition of a vehicle seat assembly comprising: a base; an upper slide member supported for movement toward and away from said base; and at least one guiding rib extending from one of said upper slide member and said base toward the other of said upper slide member and said base so as to guide movement of said upper slide member toward and away from said base.
 2. A vehicle occupant sensing system as set forth in claim 1 wherein said guiding rib extends from one of said upper slide member and said base and slidably contacts the other of said upper slide member and said base.
 3. A vehicle occupant sensing system as set forth in claim 1 wherein said base defines an axis and said guiding rib guides movement of said upper slide member substantially along the axis.
 4. A vehicle occupant sensing system as set forth in claim 1 wherein said guiding rib is mounted to said upper slide member.
 5. A vehicle occupant sensing system as set forth in claim 1 wherein said guiding rib is polished.
 6. A vehicle occupant sensing system as set forth in claim 1 wherein said guiding rib extends from one of said upper slide member and said base and slidably contacts an inner surface of the other of said upper slide member and said base, wherein said inner surface is polished.
 7. A vehicle occupant sensing system as set forth in claim 1 including a plurality of said guiding ribs that are evenly spaced about at least one of said upper slide member and said base.
 8. A vehicle occupant sensing system as set forth in claim 1 wherein said guiding rib is integrally attached to at least one of said upper slide member and said base.
 9. A vehicle occupant sensing system as set forth in claim 1 wherein said guiding rib is mounted to said upper slide member and said guiding rib includes a lower end with an axial length that is longer than an axial length of said upper slide member.
 10. A vehicle occupant sensing system as set forth in claim 9 wherein said base includes at least one opening into which said lower end enters when said upper slide member moves toward said base.
 11. A vehicle seat assembly comprising: a seat cushion with a lower surface; and a vehicle occupant sensing system disposed adjacent said lower surface of said seat cushion, said vehicle occupant sensing system including a base, an upper slide member supported for movement toward and away from said base, and at least one guiding rib extending from one of said upper slide member and said base toward the other of said upper slide member and said base so as to guide movement of said upper slide member toward and away from said base.
 12. A vehicle seat assembly as set forth in claim 11 wherein said guiding rib extends from one of said upper slide member and said base and slidably contacts the other of said upper slide member and said base.
 13. A vehicle seat assembly as set forth in claim 11 wherein said base defines an axis and said guiding rib guides movement of said upper slide member substantially along the axis.
 14. A vehicle seat assembly as set forth in claim 11 wherein said guiding rib is mounted to said upper slide member.
 15. A vehicle seat assembly as set forth in claim 11 wherein said guiding rib is polished.
 16. A vehicle seat assembly as set forth in claim 11 wherein said guiding rib extends from one of said upper slide member and said base and slidably contacts an inner surface of the other of said upper slide member and said base, wherein said inner surface is polished.
 17. A vehicle seat assembly as set forth in claim 11 including a plurality of said guiding ribs that are evenly spaced about at least one of said upper slide member and said base.
 18. A vehicle seat assembly as set forth in claim 11 wherein said guiding rib is integrally attached to at least one of said upper slide member and said base.
 19. A vehicle seat assembly as set forth in claim 11 wherein said guiding rib is mounted to said upper slide member and said guiding rib includes a lower end with an axial length that is longer than an axial length of said upper slide member.
 20. A vehicle seat assembly as set forth in claim 19 wherein said base includes at least one opening into which said lower end enters when said upper slide member moves toward said base. 